I received him as a housewarming gift in a 1/2 gallon tank. I didn't know any better at the time, so I thought it would be ok. a couple of weeks after I got him i saw a small tear in his tail. I freaked out and thought he was dying, so i started a bettafix regime along with 50% water changes every other day. after 10 days or so, i hadn't noticed a significant change. after i had come home from a weekend at my parents, i noticed he had several new rips in his tail. I immediately got him a 1.5 gallon tank and started adding aquarium salt, along with the water changes. his behavior seems healthy though, he follows my finger, he eats 3 bloodworms a day, and he is very active (his swimming doesn't seem to be affected).

what should i do, and is this life threatening to him?

ps: the edges of his fins are naturally black and silver, that is just his coloring, so i am not sure if it could be fin rot or not.